Explosion-proof fan for coal mines

The explosion-proof fan for coal mines is the core equipment of the ventilation system in coal mines, commonly known as the "lung" of the mine. It is specifically designed to deliver fresh air underground, exhaust gas, carbon monoxide, coal dust, and blasting fumes. All models used in underground mines must bear the MA coal safety mark and comply with ExdI explosion-proof and flameproof standards to prevent gas and coal dust explosions, meeting the mandatory requirements of the "Coal Mine Safety Regulations".

1. Three major types

1. Main fan (main ventilator, FBCDZ series, ground machine room)

The entire mine/mining area is equipped with general ventilation that operates continuously for 24 hours. It features a dual-machine configuration, with one in operation and the other as a standby. The system is powered by dual circuits and must possess a wind reversal function, allowing for rapid change of airflow direction in case of a fire emergency.

Mainstream: Counter-rotating axial fan with two-stage impellers rotating in opposite directions, featuring high air volume and high static pressure; adjustable blade angles to adapt to different ventilation resistances in mines

Installation: Ground return air shaft machine room

Accessories: air reversing damper, diffuser, silencer, shock-absorbing base, online monitoring system, explosion-proof frequency converter

2. Local ventilation fan (auxiliary fan, underground heading face, FBD/FBCD)

Specially designed for single-end heading tunnels, it is equipped with a flame-retardant and anti-static air duct for air supply, making it a necessity for mining and excavation.

FBD press-in type counter-rotating local fan: fresh air is sent into the heading of the tunneling, most commonly used in low-gas mines

FBCD extractable counter-rotating local fan: It directly extracts contaminated air containing gas, suitable for high-gas, coal and gas outburst mines. Features: small size, high wind pressure, long-distance air supply; regulations mandate wind and electricity interlocking, gas and electricity interlocking, automatic shutdown in case of power failure/gas exceeding standards, one in operation and one standby.

3. Auxiliary ventilator (auxiliary fan)

Pressurization of underground tunnels and balancing of pipe network resistance are commonly used in long-distance tunnels and areas with uneven ventilation resistance.

II. Core structure (mainly counter-rotating axial flow)

The machine casing, two-stage explosion-proof motor, two sets of impellers, bearing box, inlet air regulating valve, and diffuser; the supporting components are the complete set of accessories introduced earlier: inlet and outlet flexible connectors, muffler, shock absorber, coupling, shield, and explosion-proof electric control cabinet. The impellers are mostly made of wear-resistant steel plates, and wear-resistant coating can be applied for dust-wash conditions.

III. Mandatory Safety Requirements (Key Points)

1. MA coal safety mark: a necessary qualification for underground coal mine equipment. Without MA, it is strictly prohibited to enter the mine

2. Explosion-proof grade ExdⅠ Mb: flameproof enclosure, internal explosion will not ignite external gas and coal dust

3. Main fan: dual power supply, standby fan, wind reversing device, online monitoring (vibration, temperature, air volume)

4. Auxiliary fan: Equipped with flame-retardant and anti-static air duct, wind and electricity interlocking, and gas and electricity interlocking, it is strictly prohibited to use one auxiliary fan for multiple tunneling faces

5. The entire machine is wear-resistant, dust-proof, and has rust-proof maintenance on the explosion-proof surface. Continued use is strictly prohibited if the explosion-proof surface is damaged

IV. Key parameters for model selection

1. Type: Main fan / Auxiliary fan; Forced entry / Extraction

2. Air volume, total pressure, and total mine resistance

3. Medium: Gas concentration, coal dust, temperature

4. Power supply voltage: 380V/6kV/10kV; whether it is frequency conversion speed regulation or not

5. Auxiliary facilities: noise reduction, shock absorption, online monitoring, and wind reversal (main fan)

V. Common faults

1. Impeller is subject to dust accumulation and wear, resulting in damage to dynamic balance and excessive vibration

2. Rusting and collision of explosion-proof surfaces, explosion-proof failure, and major safety hazards

3. Excessive temperature rise of the bearing and poor lubrication

4. Air leakage in the ventilation duct, insufficient air volume at the front, and gas accumulation

5. The air door is stuck, and the reverse air function is malfunctioning